Imaging anatomy and variation of vertebral artery and bone structure at craniocervical junction

The objective of this article is to display the vertebral artery and bone structure at the craniocervical junction (CJVA and C_0-1-2) with three-dimensional CT angiography (3DCTA) and identify their anatomic features and variations. Eighty-eight subjects without pathology of vertebral artery (VA) and C_0-1-2 were selected from head–neck CTA examination. 3D images were formed with volume rendering (VR) and multiplanar reconstruction (MPR). On the 3D images, CJVA and C_0-1-2 were measured, and their variations were observed. CJVA goes along C_0-1-2 with five curves, of which three curves are visibly away from C_0-1-2, one is 0.0–8.3 mm away at the second curve with 0.0–11.2 mm in width, another is 0.0–9.2 mm away at the fourth with 2.8–14.8 mm and the other is 0.0–6.2 mm away at the fifth. Statistical comparisons show that there is no significant difference in the measurements between left and right, and that the curves become smaller and farther away from C_0-1-2 with the increase of age. CJVA is not equal in size, with the biggest in the fourth curve and the smallest in the fifth. Statistical comparison shows the left CJVA is larger than the right in the fifth curve. Variations were found on CJVA in 16 cases and on C₁ in 12 cases. The anatomy and variations of CJVA and C_0-1-2 are complicated. It is of vital significance to identify their anatomic features in clinical practice.